Measurement of Troponin I in blood is an important step in the diagnosis of a myocardial infarction.
State-of-the-art biological analysis of Troponin I is based on laboratory high-sensitivity heterogeneous immunoassays with luminescence detection. This involves the emission of light from a chemical reaction, or the visualization of an emitting label. Using such immunoassays results in immunoassay sensitivities in the order of pg/mL. Generally, these assays are performed on large automated detection systems designed for high throughput measurements and are not suitable for rapid testing outside of centralized laboratories by non-technical users.
Immunoassays that use magnetic labels as detection labels are known in the prior art. Such assays enable magnetic actuation and reduce the assay time. In these assays, magnetic labels are sterically hindered due to their large dimensions and do not bind to a surface with molecular receptors as easily as molecular labels (such as radioactive iodine, enzymatic label etc.). Moreover, because labels are magnetized during the assay, the duration of contact between labels increases, which enhances the probability that the magnetic labels irreversibly aggregate and quantitative information is lost. This can be a significant problem when larger magnetic particles (>200 nm) are used as they are more prone to form irreversible clusters.